The present invention relates to a timing adjustment system in a copying machine.
Generally, there are two types of timing control systems for controlling the copy paper supply timing in a copying machine. The first type includes a slit plate secured to a shaft of a photosensitive drum. The slit plate has a plurality of slits formed at predetermined positions. Each slit provides a control signal for activating respective elements in the copying machine at desired timings. In this type of timing control system, the installation of the slit plate requires a high degree of accuracy. Moreover, the first type of control system is not applicable to a copying machine having an endless photosensitive drum.
The second type of timing control system includes a slit plate which has slits periodically formed at a predetermined interval. The second type further includes a detection switch for detecting the start point of the reciprocating optical system. A control signal is developed when a predetermined number of slits are counted after generation of a detection signal from the detection switch, the control signal being applied to a drive system for activating the elements in the copying machine. This type of conventional system can not avoid the error up to the period of the slits. If the error should be reduced, the slit interval must be reduced. This will complicate the slit detection system. Furthermore, even when the fine slit is formed, there still exists the error determined by the interval of the slits.
To minimize the timing error in the above-mentioned second type of control system, a timing adjustment system has been developed. An example is disclosed in my allowed copending application, "COPY PAPER SUPPLY TIMING CONTROL IN A COPYING MACHINE", Ser. No. 506,973 filed on June 23, 1983, now U.S. Pat. No. 4,547,062. In this adjustment system, the copy paper supply timing is controlled so that the copy paper supply is initiated when a preselected time (T) has passed after a predetermined number (N) of slits have been counted from the development of a detection signal derived from an optical system start detection sensor. The preselected time (T), which is selected shorter than a period t' of the slit output, functions to adjust the accurate timing for conducting the copy paper supply. This adjustment system further includes a control circuit for compensating the displacement of the timing in the occurence of the first slit pulse. The control circuit includes a timer for counting a time period (t) from the development of the detection signal from the optical system start detection sensor to the occurence of the first slit pulse. If the time period (t) is shorter than or equal to the preselected time (T), the copy paper supply is initiated when (T-t) seconds have passed after the predetermined number (N) of slits have been counted. If the time period (t) is longer than the preselected time (T), the copy paper supply is initiated when (T+t'-t) seconds have passed after the (N-1) slits have been counted.
However, the above-mentioned timing adjustment system is not satisfactory because the preselected time (T) differs depending on the operating condition of the copying machine. In the above-mentioned timing adjustment system, it is difficult to modify the predetermined number (N) and the preselected time (T) by taking account of the actual operating condition of the copying machine.
Accordingly, an object of the present invention is to provide a modification system for modifying the timing control constants in a timing adjustment system of a copying machine.
Another object of the present invention is to provide a keyboard controlled modification system for modifying the preselected time (T) and the predetermined number (N) depending on the actual operating condition of the copying machine.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, a mode selection switch is provided for selectively placing the copying machine in a preset mode wherein the preselected time (T) and the predetermined number (N) are preset by taking into account the actual operating condition of the copying machine.